Could psychoactive drugs help “lazy people” be more physically active?

Why is it OK to treat one thing with psychoactive drugs but morally deplorable for another? Our expert follows up on his October proposal to use drugs to motivate people to exercise.

By Samuele M Marcora, Director of Research, School of Sports and Exercise Sciences, University of Kent, Canterbury.

The health costs of physical inactivity are substantial. Physical inactivity is associated with reduced lifespan and increased risk of disability, cardiovascular disease, hypertension, diabetes, certain types of cancer, and dementia. On the hand physical activity prevents and manages obesity, improves mental health, and increases quality of life for people affected by a number of chronic conditions. This list of benefits gives physical activity a strong case in being called a “miracle cure”.

Why then does less than half of the EU adult population meet the current physical activity guidelines and even less in the USA? In my opinion we have never payed enough attention to the core psychobiological reason for physical inactivity: humans are inherently “lazy.” By lazy I mean that humans have a natural tendency to avoid effort, a principle of human behaviour well established since 1943. Unfortunately, even moderate-intensity physical activity requires considerable effort compared to sedentary leisure-time activities like watching TV or surfing the internet. So it is not surprising that most people, when faced with daily decisions like “Do I go out for a walk/run or do I sit on my sofa watching television?” choose the latter.

The scope of the problem encouraged me to make a proposal late last month. In my article, I suggested the use of psychoactive drugs like caffeine or methylphenidate and modafinil to reduce perception of effort and, thus, facilitate physical activity behaviour. This novel strategy has been described as “doping for lazy people” because caffeine was included in the World Anti-Doping Agency (WADA) list of prohibited substances until 2004, and both methylphenidate and modafinil are still banned. In addition to these stimulants, I also propose the use of psychoactive drugs to enhance the so-called “runner’s high” because, if enhanced, the positive feelings experienced after exercise may provide immediate rewards which are more motivational than delayed and probabilistic rewards (e.g. a reduced risk of developing coronary heart disease in 20-years).

While I acknowledged that this proposal may seem somewhat drastic, the media’s response was telling. The proposal was described as a “radical new solution”, “Just don't try to tell your doctor …” and “Drastic? Sure. Controversial? No doubt.” However, the use of psychoactive drugs to facilitate healthy behaviours is not new. Nicotine is widely used to help people quit smoking and various appetite suppressants have been approved to help obese people stick to a hypocaloric diet. Furthermore, methylphenidate, modafinil and especially caffeine are widely used and have a good safety profile. So it is quite surprising that my proposal to use psychoactive drugs to facilitate physical activity behaviour has never been seriously considered. I have two explanations for this.

Firstly, like Sherlock Holmes would say “there is nothing more deceptive than an obvious fact”. Effort is both an intrinsic feature of physical activity and a major barrier to its long-term maintenance. These two facts are so obvious that most research has been devoted to other individual (e.g. self-efficacy) and environmental (e.g. walking and cycling facilities) correlates of physical activity behaviour. Furthermore, I and most of my colleagues in sport and exercise sciences are former athletes. Therefore, we generally have a negative attitude towards stimulants and other drugs used to enhance athletic performance (doping). This sport-specific cultural bias may have prevented the development or publication of the idea to use psychoactive drugs to facilitate physical activity behaviour. More generally, the ethics of using stimulants for cognitive and motivational enhancement is also being debated, and various concerns have been raised.

Clearly, more ethical research is needed in this area. However, if we consider physical inactivity as a medical problem of pandemic proportions many of the ethical concerns raised about the use of psychoactive drugs to enhance athletic, academic and professional performance may not be relevant. A sound societal debate on the use of psychoactive drugs to facilitate physical activity behaviour should be based on evidence concerning safety, efficacy and cost-effectiveness. It is my hope that my article will be followed by both basic and clinical research to test existing stimulants and develop even more powerful and safer drugs to reduce perception of effort and enhance the rewarding properties of physical activity.